Welding Tips and Tricks

Need a little help in trying to eliminate this blemish at the start of my weld.

I am using a Fanuc robot with a Fronius TPS 500i welder. My CTWD is high (>30mm), which I cannot decrease due to the high flared bevel weld groove. I cannot change my consumables as well. I am using the Special 2-Step Mode. Any information that could be provided is greatly appreciated!

Has Fronius been of no help? I'm wondering what they would say....

Can you adjust your preflow? I keep mine set for about a half second or one second.

I tried contacting Fronius but they never responded (via their website contact form). I'm an integrator that works with all types of welders, but since we're owned by a company that is a competitor to Fronius, they might not be too concerned with my problems.

My preflow is defaulted to 0.5 seconds. Would increasing it to 1.5-2 seconds help me get rid of the blemish?

Have you always had that blemish? If it is a gas-coverage issue, then increasing the pre-flow might help. It all depends what is causing the blemish in the first place. Does the rest of the weld look ok?

This is a cell that I'm programming for a customer so I'm in the process of developing the weld. Due to the excessive stickout (>30mm), I think that the arc "jumps" around when trying to strike an arc on this weld in particular. Once the arc stabilizes, the rest of the weld looks good.

Bump up to the 2 second preflow and try it again. Also it’s a long stickout keeping your cfm down as low as possible becomes important, especially on odd shapes or outside corners. To fast of flow can cause swirling in the gas stream and may even be drawing in air.

Stick out too long? Can you acquire a tapered gas nozzle and tapered contact tip to get your gun in closer to the work?